Signed integer overflow _fnlHash2D

[Vaxeral]

Hi. The library seems to have undefined behavior, specifically signed integer overflow.
include/FastNoiseLite.h:484:10: runtime error: signed integer overflow: 1337 * 668265261 cannot be represented in type 'int'

static inline int _fnlHash2D(int seed, int xPrimed, int yPrimed)
{
    int hash = seed ^ xPrimed ^ yPrimed;

    hash *= 0x27d4eb2d;
    return hash;
}

Is this intended, if so what is the reason?

[Auburn]

The overflow is intended it's part of the hashing algorithm

[Vaxeral]

Right and it will work almost always.
There are cases where signed integer overflow being undefined behavior can cause confusion.

int foo(int x) {
    return x+1>x;
}

The optimizer will take advantage of this fact and return 1 regardless of the value x + 1 which may overflow.

But more importantly direclty importing the c library into a zig code base is affected by this issue. Because zig is very strict about violating undefined behavior the example fails in debug builds. This can easily be fixed on zig side by using the overflow operator. Just thought I'd share.